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Electric vehicles are becoming more popular in the market. To be competitive, manufacturers need to produce vehicles with a low energy consumption, a good range and an acceptable driving performance. These are dependent on the choice of components and the topology in which they are used. In a conventional gasoline vehicle, the powertrain topology is constrained to a few well-understood layouts; these typically consist of a single engine driving one axle or both axles through a multi-ratio gearbox. With electric vehicles, there is more flexibility, and the design space is relatively unexplored. In this paper, we evaluate several different topologies as follows: a traditional topology using a single electric motor driving a single axle with a fixed gear ratio; a topology using separate motors for the front axle and the rear axle, each with its own fixed gear ratio; a topology using in-wheel motors on a single axle; a four-wheel-drive topology using in-wheel motors on both axes. Multi-objective optimisation techniques are used to find the optimal component sizing for a given requirement set and to investigate the trade-offs between the energy consumption, the powertrain cost and the acceleration performance. The paper concludes with a discussion of the relative merits of the different topologies and their applicability to real-world passenger cars. [ABSTRACT FROM AUTHOR]

The integrated longitudinal and lateral dynamic motion control is important for four wheel independent drive (4WID) electric vehicles. Under critical driving conditions, direct yaw moment control (DYC) has been proved as effective for vehicle handling stability and maneuverability by implementing optimized torque distribution of each wheel, especially with independent wheel drive electric vehicles. The intended vehicle path upon driver steering input is heavily depending on the instantaneous vehicle speed, body side slip and yaw rate of a vehicle, which can directly affect the steering effort of driver. In this paper, we propose a dynamic curvature controller (DCC) by applying a the dynamic curvature of the path, derived from vehicle dynamic state variables; yaw rate, side slip angle, and speed of a vehicle. The proposed controller, combined with DYC and wheel longitudinal slip control, is to utilize the dynamic curvature as a target control parameter for a feedback, avoiding estimating the vehicle side-slip angle. The effectiveness of the proposed controller, in view of stability and improved handling, has been validated with numerical simulations and a series of experiments during cornering engaging a disturbance torque driven by two rear independent in-wheel motors of a 4WD micro electric vehicle. [ABSTRACT FROM AUTHOR]

An Electrical Vehicle (EV) has the advantage of being friendly with environment but it does not have the same performance as a current conventional vehicle. This work proposes a strategy to improve the EV autonomy. At first, an EV model that combines lead acid batteries and a DC motor is described. The individual mathematical model for each component is developed in MATLAB. Moreover, the control speed strategy using fuzzy logic is applied to the system to produce a maximum speed reference of an EV under different states of charge of the battery and acceleration. Then, a proportional integral control adjusts the speed strategy. When the vehicle is subjected to different scenarios, the simulation realized in MATLAB/Simulink will show good efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a robotic vehicle for a personal mobility with electric-driven three-wheels is proposed. Before designing the proposed robotics vehicle, omni-directional motions using special wheels, active caster wheels, and active steerable driving wheels are studied. For design of the proposed vehicle, we discuss about active steerable wheel design, and vehicle's frame design. The omni-directional motion through the digital design exploration of the vehicle using active driving and steering wheel robot technology is examined. As the major mechanical components, an active steerable driving wheel, in-wheel motors, brakes, suspensions, and control systems are described. The design is established by rapid prototyping model of omni-directional motion. The steering geometry and control algorithm for the prototype of the proposed personal mobility are experimented. [ABSTRACT FROM AUTHOR]

In this paper, a novel direct yaw control method based on driver operation intention for stability control of a distributed drive electric vehicle is proposed. It was discovered that the vehicle loses its stability easily under an emergency steering alignment (EA) problem. An emergent control algorithm is proposed to improve vehicle stability under such a condition. A driver operation intention recognition module is developed to identify the driving conditions. When the vehicle enters into an EA condition, the module can quickly identify it and transfer the control method from normal direct yaw control to emergency control. Two control algorithms are designed. The emergency control algorithm is applied to an EA condition while the adaptive control algorithm is applied to other conditions except the EA condition. Both simulation results and real vehicle results show that: The driver module can accurately identify driving conditions based on driver operation intention. When the vehicle enters into EA condition, the emergent control algorithm can intervene quickly, and it has proven to outperform normal direct yaw control for better stabilization of vehicles. [ABSTRACT FROM AUTHOR]

The handling behaviour of vehicles is an important property for its relation to performance and safety. In 1970s, Pacejka did the groundwork for an objective analysis introducing the handling diagram and the understeer coefficient. In more recent years, the understeer concept is still mentioned but the handling is actively managed by direct yaw control (DYC). In this paper an accurate analysis of the vehicle handling is carried out, considering also the effect of drive forces. This analysis brings to a new formulation of the understeer coefficient, which is almost equivalent to the classical one, but it can be obtained by quasi-steady-state manoeuvres. In addition, it relates the vehicle yaw torque to the understeer coefficient, filling up the gap between the classical handling approach and DYC. A multibody model of a Formula SAE car is then used to perform quasi-steady-state simulations in order to verify the effectiveness of the new formulation. Some vehicle set-ups and wheel drive arrangements are simulated and the results are discussed. In particular, the handling behaviours of the rear wheel drive (RWD) and the front wheel drive (FWD) architectures are compared, finding an apparently surprising result: for the analysed vehicle the FWD is less understeering than for RWD. The relation between the yaw torque and the understeer coefficient allows to understand this behaviour and opens-up the possibility for different yaw control strategies. [ABSTRACT FROM AUTHOR]

In this paper, the optimal power distribution of the front and rear motors for minimizing energy consumption of a 4WD EV is investigated. An optimal power distribution control is developed based on the mathematical energy consumption model of an EV. The objective function is defined while ignoring time. And, the time effect is applied by considering the objective function for every single driving point which consists of the vehicle driving force and velocity. From the optimization problem, the optimal torque distribution maps of the front and rear motors can be obtained for all vehicle driving force and velocity ranges. These maps can be expressed using a 3-dimensional map. If the vehicle driving force and velocity are determined, the optimal front and rear motor torques can be determined using these maps. These maps can distribute the front and rear motor torques for the entire velocity range. Thus, these maps can perform the optimal power (torque times speed) distribution of the front and rear motors for minimizing the energy consumption of the 4WD EV. The performance of the optimal power distribution is evaluated by comparing the energy consumption to that of simple power distribution control. For obtaining the energy consumption, a vehicle driving simulation is performed. For the simulation, the driving cycle is required, and the NEDC (New European Driving Cycle) is used. From the simulation results, it is found that the energy consumption of simple power distribution is 4.8 % larger than the optimal one. Thus, the optimal power distribution can minimize the 4WD EV energy consumption as the optimization objective function. [ABSTRACT FROM AUTHOR]

In this paper we propose a constrained optimal control architecture for combined velocity, yaw and sideslip regulation for stabilisation of the vehicle near the limit of lateral acceleration using the rear axle electric torque vectoring configuration of an electric vehicle. A nonlinear vehicle and tyre model are used to find reference steady-state cornering conditions and design two model predictive control (MPC) strategies of different levels of fidelity: one that uses a linearised version of the full vehicle model with the rear wheels' torques as the input, and another one that neglects the wheel dynamics and uses the rear wheels' slips as the input instead. After analysing the relative trade-offs between performance and computational effort, we compare the two MPC strategies against each other and against an unconstrained optimal control strategy in Simulink and Carsim environment. [ABSTRACT FROM AUTHOR]

This paper describes torque distribution control of six-wheeled in-wheel motor vehicles by considering the friction circle of each wheel for enhanced terrain-driving performance. Using control allocation, the proposed torque distribution algorithm determines the torque command to each wheel, by considering the size of the friction circle. The friction circle of each wheel is estimated using a linear parameterized tyre model with two threshold values. The parameters and the threshold values are computed from measurements of the wheel speed, the yaw rate, the acceleration and the torque command signals using a recursive least-squares method. Simulation studies were conducted using TruckSim and MATLAB/Simulink co-simulations. It was confirmed that the proposed friction circle estimation algorithm can be successfully used for torque distribution to enhance the terrain-driving and hill-climbing performance. [ABSTRACT FROM AUTHOR]

For a hybrid car equipped with dual clutch transmission (DCT), the coordination control problems of clutches and power sources are investigated while taking full advantage of the integrated starter generator motor's fast response speed and high accuracy (speed and torque). First, a dynamic model of the shifting process is established, the vehicle acceleration is quantified according to the intentions of the driver, and the torque transmitted by clutches is calculated based on the designed disengaging principle during the torque phase. Next, a robustH∞controller is designed to ensure speed synchronisation despite the existence of model uncertainties, measurement noise, and engine torque lag. The engine torque lag and measurement noise are used as external disturbances to initially modify the output torque of the power source. Additionally, during the torque switch phase, the torque of the power sources is smoothly transitioned to the driver's demanded torque. Finally, the torque of the power sources is further distributed based on the optimisation of system efficiency, and the throttle opening of the engine is constrained to avoid sharp torque variations. The simulation results verify that the proposed control strategies effectively address the problem of coordinating control of clutches and power sources, establishing a foundation for the application of DCT in hybrid cars. [ABSTRACT FROM PUBLISHER]

Agricultural operations are constantly becoming technology-driven mainly due to labor shortages, increase in labor cost, and trends in new and advanced technology applications. In this paper, we have presented a system-of-systems approach to design and development of a mobile robotic platform for agricultural applications. Similar to other field robots, the mobile platform for agricultural applications requires a different set of predefined attributes for its operation. We have designed, fabricated, and demonstrated the mobile platform for pesticide spraying application. The design and development includes synergistic integration of mechanical, sensor and actuator, navigational and control, and electronic and software interfacings. The autonomous navigation aspect of the development was achieved via three stages: learning stage, implementation stage (training stage), and testing stage. In the learning stage, we defined the path patterns and studied and recorded the behavior of the vehicle in real-world environment. In the training stage, various steering algorithms for four-wheel driving system were developed and inherent errors were compensated using advanced tools and methods. In the testing stage, we put the robotic platform on an arbitrary path pattern and demonstrated its success in autonomous navigation. The medium-sized mobile robot can be commercialized for greenhouse-based agricultural operations. [ABSTRACT FROM PUBLISHER]

In this paper, the novel design of a side-slip angle observer and an observer-based stability controller for a vehicle with a non-linear tyre model and a varying forward speed is presented. The Takagi–Sugeno fuzzy modelling technique is first applied to represent the vehicle’s lateral dynamics with the non-linear Dugoff tyre model and varying speed. The observer and the observer-based controller are then constructed using the measured yaw rate and the estimated premise and state variables and are designed to be robust against the model and parameter uncertainties. The conditions for designing such an observer and an observer-based controller are derived in terms of linear matrix inequalities. Numerical simulations on a non-linear eight-degree-of-freedom vehicle dynamics model and experimental data are conducted to validate the effectiveness of the proposed approach. The comparison of results with those from other existing approaches shows that the designed observer can accurately estimate the vehicle’s side-slip angle and the controller can effectively control this side-slip angle regardless of the variation in the vehicle’s longitudinal velocity. [ABSTRACT FROM PUBLISHER]

As an important development direction of pure electric vehicle drive system, the distributed drive system has the advantages of compact structure, high transmission efficiency, and flexible control, but there are some serious problems such as high performance requirements to the drive motors, complex control strategies, and poor reliability. To solve these problems, a two motors dual-mode coupling drive system has been developed at first, which not only has the capacity of two-speed gear shifting, but also can automatically switch between the distributed drive and the centralized drive by means of modes change control. So, the performance requirements to the drive motors can be reduced, the problem of abnormal running caused by the fault of unilateral distributed drive systems also can be resolved by replacing the drive mode with centralized drive. Then, the system parameters primary and the optimum matching under the principle of efficiency optimization have been carried out, which makes the drive system achieve predetermined functions and meet the actual demands of different operating statuses. At last, the economic comparison of a pure electric vehicle installation with a dual-mode coupling drive system, a single-motor centralized drive system or a dual-motor distributed drive system in the simulation conditions has been completed. Compared with other systems, the driving range of the electric vehicle driven by the designed system is significantly increased, which proves the better efficiency and application value of the system. [ABSTRACT FROM AUTHOR]

This paper presents an acceleration slip regulation (ASR) system for four-wheel drive (4WD) electric vehicles, which are driven by the front and rear axles simultaneously. The ASR control strategy includes three control modes: average distribution of inter-axle torque, optimal distribution of inter-axle torque and independent control of optimal slip rate, respectively, which are designed based on the torque adaptive principle of inter-axle differential and sliding mode control theory. Furthermore, in order to accurately describe the longitudinal tyre force characteristic, a slip rate calculation formula in the form of a state equation was used for solving the numerical problem posed by the traditional way. A simulation was carried out with the MATLAB/Simulink software. The simulation results show that the proposed ASR system can fully use the road friction condition, inhibit the drive-wheels from slipping, and improve the vehicle longitudinal driving stability. [ABSTRACT FROM AUTHOR]

An author index for the January/February 2013 issue of the journal "IEEE Transactions on Industry Applications" is presented.

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author's name. The primary entry includes the co-authors' names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author's name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index. [ABSTRACT FROM AUTHOR]

This study involves a layered vehicle dynamics control system, which is composed of an adaptive optimal control allocation method using Lagrangian neural networks for optimal distribution of tyre forces and the sliding mode yaw moment observer for robust control of yaw dynamics. The proposed optimal control allocation method eliminates the requirement of solving optimization problem in every time step and it is a convergent and stability guaranteed solution for the optimal tyre force distribution problem. The aim in the sliding mode yaw moment observer is to force the vehicle to track a reference vehicle dynamic behaviour by estimating the equivalent input extended disturbance, which is the required stabilizing virtual yaw moment. The proposed layered stability control scheme has been tested on a four-wheel drive–four-wheel steer electric Fiat Doblo Van, which is modelled in CarSim. Both the sliding mode disturbance observer and the optimal control allocation methods are the first known applications to the stability control problem of road vehicles. [ABSTRACT FROM AUTHOR]

Electric vehicle is considered to be the solution for energy and environment crisis, but it's still not competitive enough with conventional vehicles because of the limited energy density and high cost of the power battery. So the energy efficiency is of the most importance for the control of electric vehicles. This paper looks into the energy efficiency optimization problem of electric vehicle driven by four in-wheel motors by developing a comprehensive energy efficiency model of the permanent magnet synchronous motor including the inverter. The calculated efficiency agrees with the measured data quite well. Based on the power loss analysis, the conclusion is drawn that in all driving or braking conditions the total torque requirement should be distributed evenly to all the motors in order to maximize the energy efficiency for electric vehicles driven by permanent magnet synchronous in-wheel motors. Vehicle test results show that the energy efficiency of the evenly distributed torque control is higher than the control strategy proposed by control allocation in literature. [ABSTRACT FROM AUTHOR]

The dynamic model of a novel electric power steering (EPS) system integrated with active front steering function (the novel EPS system) is built. The concepts and quantitative expressions of the steering road feel, steering sensibility, and steering operation stability are introduced. Based on quality engineering theory, the optimization algorithm is proposed by integrating the Monte Carlo descriptive sampling, elitist non-dominated sorting genetic algorithm (NSGA-II) and 6-sigma design method. With the steering road feel and the steering portability as optimization targets, the system parameters are optimized by the proposed optimization algorithm. The simulation results show that the system optimized based on quality engineering theory can improve the steering road feel, guarantee steering stability and steering portability and thus provide a theoretical basis for the design and optimization of the novel electric power steering system. [ABSTRACT FROM AUTHOR]